Fan power supply control system

ABSTRACT

A fan power supply control system includes a power supply module, a power control circuit, a signal control circuit, a PWM generator. The power supply is adapted to input a power signal to a fan. The power control circuit is between the power supply module and the fan and adapted to connect or disconnect the power supply module to the fan. The signal control circuit is connected the power supply module to the power control circuit and adapted to switch on or off the power control circuit. The PWM generator is adapted to generate a predetermined cycle square signal according to the power signal, to intermittently switch on or off the signal control circuit, and a switch on/off state of the power control circuit is synchronous with the signal control circuit.

BACKGROUND

1. Technical Field

The present disclosure relates to a fan power supply control system.

2. Description of Related Art

A computer system sometimes includes a fan for dissipating heatgenerated by heat generation component, such as central processing unit(CPU). Usually, the fan is provided with a power supply circuit. Thepower supply circuit supplies power to the fan and includes a pluralityof transistors. When the fan starts, the power supply circuit maygenerate a current spike and damage the plurality of transistors.Therefore, there is a need for improvement in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a block view of an embodiment of a fan power supply controlsystem.

FIG. 2 is a circuit view of the fan power supply control system of FIG.1.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean “at least one.”

FIG. 1 shows one embodiment of a fan power supply circuit includes apower supply module 20, a filtering circuit 30, a power control circuit50, a signal control circuit 60, a pulse width modulation (PWM)generator 70, and a charging and discharging circuit 80.

The power supply module 20 provides a power to a fan 90. In oneembodiment, the power supply module 20 may input a power signal with acurrent spike, and the current spike has a predetermined time. Thefiltering circuit 30 is electrically coupled to the power supply module20 and adapted to filter a power signal input by the power supply module20. The signal control circuit 60 is electrically connected to the powercontrol circuit 50 and the filtering circuit 30. The signal controlcircuit 60 is adapted to switch on or off the power control circuit 50.The PWM generator 70 is electrically connected to the signal controlcircuit 60 and adapted to control the signal control circuit 60 to beswitched on or off. The charging and discharging circuit 80 iselectrically coupled to the power control circuit 50 and the fan 90.

FIG. 2 shows that, the filtering circuit 30 includes a first capacitorC1 and configured to filter the power signal, the first capacitor C1filtering a high frequency of the power signal, for example. A first endof the first capacitor C1 is electrically connected to a positiveelectrode of the power supply module 20, and a second end of the firstcapacitor C1 is electrically connected to a negative electrode of thepower supply module 20 and is grounded.

The power control circuit 50 is adapted to connect or disconnect thepower supply module 20 to the fan 90 and includes a first resistor R1, asecond capacitor C2, and a first MOSFET Q1. The first resistor R1 andthe second capacitor C2 are in parallel. A first end of the firstresistor R1 is electrically connected to the positive electrode of thepower supply module 20 and a first end of the second capacitor C2. Asecond end of the first resistor R1 is electrically connected to thesecond end of the second capacitor C2. A source electrode of the firstMOSFET Q1 is electrically connected to the first ends of the firstresistor R1 and the second capacitor C2. A grid electrode of the firstMOSFET Q1 is electrically connected to the second end of the firstresistor R1 and the signal control circuit 60. The drain electrode ofthe first MOSFET Q1 is electrically connected to the charging anddischarging circuit 80.

The signal control circuit 60 is a second MOSFET Q2. A source electrodeof the second MOSFET Q2 is grounded. A drain electrode of the secondMOSFET Q2 is electrically connected to the grid electrode of the firstMOSFET Q1. A grid electrode of the second MOSFET Q2 is electricallyconnected to a first end of a second resistor R2. A second end of thesecond resistor R2 is electrically connected to a working voltage VCC.The switching on/off of the power control circuit 50 is synchronous withthe signal control circuit 60.

The PWM generator 70 is electrically connected to the first end of thesecond resistor R2 and adapted to generate a predetermined square signalaccording to the power signal switching the second MOSFET Q2 on or off

The charging and discharging circuit 80 includes a third resistor R3, adiode D1, a third capacitor C3, and a fourth capacitor C4. The thirdresistor D1, the diode D1, the third capacitor C3, and the fourthcapacitor C4 are in parallel. A first end of the third resistor R3 iselectrically connected to the drain electrode of the first MOSFET Q1 andthe fan 90, and the second end of the third resistor R3 is grounded. Anegative electrode is electrically connected to the drain electrode ofthe first MOSFET Q1 and the fan 90, and a positive electrode isgrounded. A first end of the third capacitor C3 is electricallyconnected to the drain electrode of the first MOSFET Q1 and the fan 90,and a second end of the third capacitor C3 is grounded. A first end ofthe fourth capacitor C4 is electrically connected to the drain electrodeof the first MOSFET Q1 and the fan 90, and a second end of the fourthcapacitor C4 is grounded.

The power supply module 20 begins to work to provide the working voltageVCC, and the second MOSFET Q2 switches on. The first MOSFEET Q1 switcheson, and the power module 20 charges the third capacitor C3, the fourthcapacitor C4, and provides power to the fan 90. When the PWM generator70 generates a low level signal to the second MOSFET Q2, the secondMOSFET Q2 is switched off to switch off the first MOSFET Q1. At thistime, the power supply module 20 may generate the current spike, thus,the first MOSFET Q1 does not get damaged. The third capacitor C3 and thefourth capacitor C4 discharge to the fan 90. When the PWM generator 70generates a high level signal to the second MOSFET Q2, the second MOSFETQ2 is switched on to switch on the first MOSFET Q1. The power module 20continually provides power to the fan 90. When a rotating speed of thefan 90 is stable, the predetermined cycle of PWM generator 70 ends. Thesecond MOSFET Q2 continues to switch on under the working voltage VCC,to continually switch on the first MOSFET Q1. The fan 90 runs steadily.

Even though numerous characteristics and advantages of the presentdisclosure have been set forth in the foregoing description, togetherwith details of the structure and function of the disclosure, thedisclosure is illustrative only, and changes may be made in detail,especially in the matters of shape, size, and the arrangement of partswithin the principles of the disclosure to the full extent indicated bythe broad general meaning of the terms in which the appended claims areexpressed.

What is claimed is:
 1. A fan power supply control system comprising: apower supply module adapted to input a power signal to a fan; and apower control circuit being between the power supply module and the fan,and the power control circuit adapted to connect or disconnect the powersupply module to the fan; a signal control circuit connected the powersupply module to the power control circuit, and the signal controlcircuit adapted to switch on or off the power control circuit; and apulse width modulation (PWM) generator adapted to generate apredetermined cycle square signal according to the power signal, tointermittently switch on or off the signal control circuit, and aswitching on/off state of the power control circuit being synchronouswith the signal control circuit.
 2. The fan power supply control systemof claim 1, further comprising a filtering circuit electricallyconnected to the power supply module and the power control circuit,wherein the filtering circuit is adapted to filter the power signal. 3.The fan power supply control system of claim 2, wherein the filteringcircuit comprises a first capacitor, a first end of the first capacitoris electrically connected to a positive electrode of the power supplymodule, and a second end of the first capacitor is grounded.
 4. The fanpower supply control system of claim 1, wherein the power controlcircuit comprises a first resistor and a second capacitor, and the firstresistor and the second capacitor are in parallel.
 5. The fan powersupply control system of claim 4, wherein the power control circuitfurther comprises a first MOSFET, and a source electrode of the firstMOSFET is electrically coupled to a first end of the first resistor, agrid electrode of the first MOSFET is electrically connected to a secondend of the first resistor and the signal control circuit, and the drainelectrode of the first MOSFET is connected to fan.
 6. The fan powersupply control system of claim 5, wherein the signal control circuit isa second MOSFET, a drain electrode of the second MOSFET is electricallyconnected to the grid electrode of the second MOSFET, a grid electrodeof the second MOSFET is electrically connected to a second resistor, anda source electrode of the second MOSFET is grounded.
 7. The fan powersupply control system of claim 6, wherein a first end of the secondresistor is coupled to the PWM generator and the grid electrode of thesecond MOSFET, and the second end of the second resistor is connected toa work voltage.
 8. The fan power supply control system of claim 5,further comprising a charging and discharging circuit connected to thefirst MOSFET and the fan, wherein the charging and discharging comprisesa third resistor, a diode, a third capacitor, and the a fourthcapacitor, and the third resistor, the diode, the third capacitor andthe fourth capacitor are in parallel.
 9. The fan power supply controlsystem of claim 8, wherein a positive electrode of the diode isgrounded, and the negative electrode of the diode is connected to thedrain electrode of the first MOSFET.
 10. The fan power supply controlsystem of claim 6, wherein the power signal has a current spike, the PWMgenerator is adapted to generate a low level signal to switch off thesecond MOSFET when the power signal is in the current spike.
 11. A fanpower supply control system comprising: a power supply module adapted toinput a power signal to a fan; and a power control circuit being betweenthe power supply module and the fan; a signal control circuit connectedthe power supply module to the power control circuit; and a PWMgenerator adapted to generate a predetermined cycle square signalaccording to the power signal, to intermittently switch on or off thesignal control circuit, wherein the signal control circuit is switchedon when the PWM generator generates a high level signal, and the powercontrol circuit switches on to connect the power supply module to thefan; the signal is switched off when the PWM generator generates a lowlevel signal, and the power control circuit is switched off todisconnect the power supply module from the fan.
 12. The fan powersupply control system of claim 11, further comprising a filteringcircuit electrically connected to the power supply module and the powercontrol circuit, wherein the filtering circuit is adapted to filter thepower signal.
 13. The fan power supply control system of claim 12,wherein the filtering circuit comprises a first capacitor, a first endof the first capacitor is electrically connected to a positive electrodeof the power supply module, and a second end of the first capacitor isgrounded.
 14. The fan power supply control system of claim 11, whereinthe power control circuit comprises a first resistor and a secondcapacitor, and the first resistor and the second capacitor are inparallel.
 15. The fan power supply control system of claim 14, whereinthe power control circuit further comprises a first MOSFET, and a sourceelectrode of the first MOSFET is electrically coupled to a first end ofthe first resistor, a grid electrode of the first MOSFET is electricallyconnected to a second end of the first resistor and the signal controlcircuit, and the drain electrode of the first MOSFET is connected tofan.
 16. The fan power supply control system of claim 15, wherein thesignal control circuit is a second MOSFET, a drain electrode of thesecond MOSFET is electrically connected to the grid electrode of thesecond MOSFET, a grid electrode of the second MOSFET is electricallyconnected to a second resistor, and a source electrode of the secondMOSFET is grounded.
 17. The fan power supply control system of claim 16,wherein a first end of the second resistor is coupled to the PWMgenerator and the grid electrode of the second MOSFET, and the secondend of the second resistor is connected to a work voltage.
 18. The fanpower supply control system of claim 15, further comprising a chargingand discharging circuit connected to the first MOSFET and the fan,wherein the charging and discharging comprises a third resistor, adiode, a third capacitor, and the a fourth capacitor, and the thirdresistor, the diode, the third capacitor and the fourth capacitor are inparallel.
 19. The fan power supply control system of claim 18, wherein apositive electrode of the diode is grounded, and the negative electrodeof the diode is connected to the drain electrode of the first MOSFET.20. The fan power supply control system of claim 16, wherein the powersignal has a current spike, the PWM generator is adapted to generate alow level signal to switch off the second MOSFET when the power signalis in the current spike.